Ignition shielding



, Jan. 18, 1938. J. J. MAscucH ,7

IGNITION SHIELDING Filed July 11, 1931 6 Sheets-Sheet l INVENTOR 7555a?J/V/Isc'ucw l5 ATTORNEY Jan. 18, 1938. J MASCUCH 2,105,791

IGNITION SHIELDING Filed July 11, 1931 6 Sheets-Sheet 2 INVENTOR MsATTORNEY J. J. MASCUCH IGNITION SHIELDING Filed July 11 Jan. 18, 1938.

1931 6 Sheets-Sheet 3 INVENTOR 4 JESEPH JT/VAscz/cfi 6 ATTORNEY 1938..1. J. MASCUCH IGNITION SHIEL DING Filed July 11, 1931 6 Sheets-Sheet 4R O T N E V m vTosfP/v J Mas cuc /r 5 6 lf/S ATTORNEY Jan. 18, 1938. JMASCUCH 2,1Q5,791

IGNITION SHIEL DING Filed July 11, 1951 6 Sheets-Sheet 5 INVENTOR 6:I/V/ISLl/C'l/ f/l ATTORNEY Jan. 18, 1938. J. J. MAscucH' IGNITIONSHIELDING Filed July 11, 1931 6 Sheets-Sheet 6 INVENTOR JZJSEPHTIN/950110 H15 ATTORNEY Patented Jan. 18, 1938 UNITED STATES PATENTOFFICE IGNITION SHIELDING Joseph J. Mascuch, Newark, N. J. ApplicationJuly 11, 1931, Serial No. 550,076

20 Claims.

This invention relates to means for shielding the ignition system ofinternal combustion engines and is a continuation in part of applicationSerial No. 394,618, filed September 23rd, 1929.

One object of the invention is to provide a conduit system for ignitionwhich will completely isolate, electrically, the ignition system of aninternal combustion engine.

When internal combustion engines using electrical ignition systems areused in proximity to radio receiving apparatus, there is a radiation ofelectrical waves from the ignition system, which radiation causesinterference with the reception of radio equipment.

By properly surrounding with a conductive casing, allof the parts of theignition system through which high frequency currents pass and groundingthe said conducting casing, it is possible to dissipate the energy ofthe electrical radiations directly to ground, thereby preventing theaforesaid interference. It is an object of this invention to provide aconductive casing or shielding for the entire ignition system ofinternal combustion engines, whereby interference to radio communicationand equipment installed in proximity to the engine will be eliminated.

This invention is applicable to all types of combustion engines andparticularly to engines on units such as aeroplanes, motor boats,automobiles, submarines, etc. For the purpose of illustrating anddescribing the invention only its application to a radial aeroplaneengine is shown. However, this is not to be construed as a limitation ofthe uses of the invention. The invention 35 may also be used onstationary engines.

In order to provide an effective shielding means it isnecessary toshield the low and high tension conductors, the starting and switchcircuits, the spark plugs, magnetos, distributors, generator,

49 and battery, or any other means forthe production and distribution ofelectrical energy that may be used. All of the electrical equipment isinsulated. The shielding is accomplished by enclosing all of theelectrical equipment in highly 5 conductive casings or shields which aregrounded or bonded to the engine and fuselage of the aeroplane so thatany electrical radiation will be absorbed and grounded by the shields.

Due to the extreme conditions under which an 50 aeroplane engineoperates it is necessary, in order to have an effective shield, that theignition system be protected from the possibility of failure due tooutside interference. A short circuit or break in any part of theignition system will 65 cause most serious damage. Oil, water or gaso-,

line will deteriorate the insulating material, at. first permittingcorona. discharges and eventually resulting in a total breakdown of theinsulation, thereby causing the necessity for the replacement of thedefective conductor. Therefore, an- 5 other object of the invention isto provide a shielding means for the ignition system which will preventwater oil, gas or other detrimental foreign substances from reaching theconductors or other parts of the ignition system, and which, 10 byenclosing the entire system in a fireproof casing will minimize the riskof fire caused by short circuits, resistance flashes and sparking.

In order for a shielding system to be practical it must be constructedso that it may be easily 15 applied to an engine and constructed so thatparts thereof may be removed or replaced without the necessity ofdismounting the engine and removing the entire shielding means. In thepast, shields applied to aeroplane engines have been 20 placed on therear of the engine and have not been built in sections. In order toeither apply or service the shielding system it has been necessary topractically dismount the engine and the shielding means. Therefore,another object of 25 the invention is to provide a shielding systemwhich may be easily and quickly applied to the front of the enginebehind the propeller, without the necessity of disturbing the engine,and which may be made in sections so that any part may be easily andquickly removed and another part substituted without removing the entireshielding means. By placing the shielding means immediately behind thepropeller it is subject to blast of the propeller which prevents theaccumulation of oil, water, or other detrimental foreign substances onthe shields. A furtherobject of the invention is to make the jointsorconnections of such sections thoroughly water and oil proof so that nomoisture or other detrimental agents can get into the shielding means.

A further object of the invention is to provide a main manifold fromwhich sub-conduits lead to the individual spark plugs and magnetos. Inthe .past, in shielding the conductors it has been common practice todirectly shield each lead from the magneto to the spark plug, therebyin-' creasing the capacitance between the ignition conductor and ground,thereby reducing the intensity of the spark, resulting in a loss ofpower or failure of the compressed charge to ignite, thereby chargingthe exhaust manifold with an explosion maximum which subsequentlyexplodes in the manifold, greatly increasing the fire hazard. Sincetheisdmary wiring of the magnetos is grounded and the shielding isgrounded,

the greater the length of the shielding the more.

resistance will be set up in the magnetos. If this resistance rises to apoint where the magnetos are not strong enough to overcome it, theengine will miss. By using a single main manifold for all the wires thecapacitance of the shielding system is decreased and the resistance inthe magnetos materially reduced.

Where rigid shielding is used the vibration causes rapid wear andabrasion of the insulating materials of the conductors. As soon as theinsulation is damaged electrical emanations are released therefrom-withresultant loss of power and efficiency. Therefore, a further object ofthe invention is to provide flexible conduits to the spark plugs andmagnetos so that the harmful effects of vibration will be minimized.This insures longer wear and less likelihood of breakdown. Where rigidshielding is used the vibration causes the shielding to crystallize andbreak. By using flexible shielding this danger is eliminated.

In high tension conductors it is essential that the outer surface of theinsulating material be smooth and that the conductor be kept free fromkinks or sharp bends at which points charges of high potential may buildup. In case the smooth 5 or lacquered surface of the insulation becomesdamaged at points or sharp bends, the accumulated charge will create acorona discharge from the rough or fuzzy points, thereby graduallydeteriorating the entire insulating material and causing a completebreak-down of the insulation at this point, resulting in a shortcircuit. By making ,the inside of the conduits smooth, the lacquerfinish of the conductors is not damaged when they are drawn through theconduits. It is therefore a' further specific object of the invention toprovide a shielding means wherein the inner surface of the conduits willbe smooth and wherein the outlets from the main conduit will be curvedso that sharp bends and kinks in the conductors will be impossible. Bymaking the conduits larger than the conductors an air gap will be leftin the conduit around the conductors. This air gap increases theinsulation and also prevents, to a certain extent, wear andabrasion ofthe conductors.

At high altitudes or under other conditions of low atmospheric pressure,at which time the conduction of the surrounding air is very much greaterthan the conduction of the compressed gas between the gap of the sparkplug points, there is danger of the ignition current flashing over orsparking to a. nearby grounded conductor and natural sparking outlet atspark plug points. It is standardpractice to maintain a distance of atleast A;ths of an inch between any uninsulated conductor carryingignition current from any grounded part. In providing a shielding meansfor the spark plug, it would be necessary to use a large and bulkygrounded conductor to enclose the spark plug, unless other insulatingmeans is provided. It is therefore a further specific ob- J'ect of thisinvention to provide a shielding means of moderate size for the sparkplug which will provide a distance of at least ths of an inch betweenall uninsulated parts carrying high tension ignition current fromsurrounding grounded parts. Changes of temperature will causecondensation of moisture on the insulating body of the spark plugs andsnow, water or ice which may leak through the shielding means and gatheron the insulated body of the spark plug will cause a short circuit andmake it extremely difficult to start the engine without first wiping offall mois ture from the insulated body of the spark plug and spark plugleads. It is therefore a. further specific object of this invention toprovide a waterproof and air tight shielding means for the spark plugs.

The invention consists of the construction, combination and arrangementof parts as herein illustrated, described and claimed.

In the accompanying drawings, forming part hereof, is illustrated a formof embodiment of 'the invention, in which drawings similar referencecharacters designate corresponding parts, and in which:

Figure l is a front elevation of a radial aircraft engine, showing theapplication of the in vention thereto;

Figure 2 is a fragmentary detail in side elevation showing one conduitto the spark plug on the rear side of the engine;

Figure 3 is a rear elevation of a shielding sys tem, showing the mainmanifold with the flexible conduits extending therefrom;

Figure 4 is a fragmentary detail in elevation, partly in section,showing the connection between the parts of the main manifold;

Figure 5 is a rear elevation of a coupling means to the magneto, showingpart of the magneto covers;

Figure 6 is a side elevation, partly in section, of the couplings shownin Figure 5;

Figure 'I is a fragmentary detail, partly in section, showing the methodof attaching the main manifold to the crankcase;

Figure 8 is a composite plan view, partly in section, showing one outletfrom the main manifold and one type of shielded spark plug;

Figure 9 is a front elevation, partly broken away, of a spark plugshield;

Figure 10 is a vertical section taken approximately on line l0|0 ofFigure 9, looking in the direction indicated by the arrows;

Figures 11 and 12 are fragmentary details showing the method of holdingthe conduits to the engine;

Figure 13 is a horizontal section on line l3-l3 of Figure 12, lookingdownward;

Figure 14 is an enlarged detail, partly broken away, showing thestructure of the flexible conduit; and,

Figures 15 and 16 are diagrammatic plan views of modified systems ofwiring showing the use of a junction box.

Referring to the drawings 2|, d8Sigliat8S the crankcase of an aircraftengine having radial cylinder blocks 22 extending therefrom. Thecylinder blocks 22 carry push-rod casings 23 and the propeller 24 iscarried on the center of the crankcase 2|. Disposed on the crankcase 2|is a two-piece manifold 25. The manifold 25 may be of any shape orcontour desired to fit any particular engine, such as oval, straight,round, etc. The manifold 25 is here shown as being made in two parts butit may be made in one or several parts as necessity or efficiencydictates. The manifold 25 consists of a metallic tube having closedends, and having a smooth interior and a metal gasket 29 is disposedbetween the two sections to insure a tight closure and to insure a goodelectrical contact. It will be borne in mind that all connections inthis invention must be both liquidproof and made .so as to form acontinuous electrical conductor.

The manifold 25 is secured to the crankcase 2| by means of brackets 30.The brackets 30 may be disposed at any point around the manifold 25. Thebrackets 39 are silver-soldered to the manifold 25. While the brackets30 may be secured to the manifold 25 in any suitable manner it has beenfound that the use of silver solder is more efllcient, giving a strongerbond for the weight of solder used and leaving a smooth surface toprevent the accumulation of dirt, etc.- The brackets 30 are providedwith openings 3| through which studs 32 are disposed to hold themanifold 25 to the crankcase 2|, as best shown in Figure-7.

Disposed around the manifold 25, on the outside thereof, are outlets 33,for the purpose of leading the ignition wires to the spark plugs. Theoutlets 33 may be made as a part of the manifold 25 but also may be madeseparately and silver-soldered to the manifold 25. The outlets 33, as'best shown in Figure 8, comprise a tubular body 34, the center line ofwhich extends outward at right angles to the manifold 25.

The manifold end of each member 34 is flared outward on one side at 35.'The opposite side 36 describes a longer curve before reaching themanifold 25. The purpose of this curved section 36 is essary in theignition wire when passing from the manifold 25 through the outlet 33.An ad-- ditional advantage of the curved portion 36 is that it indicatesin which direction a wire will run in the manifold 25, thus assisting inarranging the proper assemblage of the ignition wires. The other end ofthe tubular member 34 is provided with a screw-threaded section 31. Onthe inside, adjacent the outer end, the member 34 is provided with abeveled face 38 for the purpose hereinafter described.

The ignition wires or conductors 39 are encased in insulation 40 andpass from the manifold 25 through the outlet 33 to the spark plugs.Disposed around the conductors 39 between the outlets 33 and the sparkplugs are conduits 4| The conduits 4| are secured to the outlets 33 bymeans of interiorly screw-threaded collar nuts 42.

The conduit 4| is fabricated from three layers of material, as bestshown in Figure 14, the inner layer. being formed of a single continuousstrip of metal 44 spun upon itself to produce a flexible housing for theconductors 39 andinsulation .40. The strip 44 may be made of anysuitable metal but is preferably made of aluminum. The Strip 44, incross-section is substantialiy the shape of a block letter S and is sospun as to provide oppositely disposed interlocking flanges 45. When thestrip 44 is spun a packing 46 is introduced between the flanges 45.

The packing 46 may be asbestos and is saturated with graphite to insurea good conducting element through the strip 44-. when the inner conduithas been spun as described air spaces 43 are left between the flanges45, thus leaving room for flexing the conduit 4|.

With this construction the inside surface 41 of the conduit 4| is madeperfectly smooth so that when the conductors 39 with the insulation 49are drawn through the conduit 4|, the lacquer finish on the insulation40 will not be damaged. Even though the conduit 4| be bent or flexed theto eliminate the sharp bend otherwise nec-.

side thereof.

inner surface 41 will still be smooth and thus preserve the insulation40. As pointed out heretofore if the insulation 40 is damaged in any waya loss in efficiency in-th ignition system will result. The inside ofthe conduit 4| is larger than the conductor 39 with its insulation 40.This leaves an air gap inside the conduit M which greatly increases theinsulating qualities and prevents abrasion of the insulation 40.

Disposed around the inner conduit formed by the strip 44 is a jacket orcasing of braided wire 49. Many types of wire may be used but it hasbeen found highly successful to use a braiding of fine-gauge tinnedcopper wire. On the outside of the conduit 4| is braided a protectivecasing or armor 49 composed of strips of metal or flat wire. Thefunction of the armor 49 is to both protect the conductor 39 and act asan electrical conductor. Therefore, many types of armor may be used.However, it has been found that for flexibility, durability, strengthand lightness, an armor made of phosphor bronze ribbon is highlysuccessful. With this construction a continuous electrical bond is madebetween the layers of the conduit 4|.

Disposed on each end of each conduit 4| is a ferrule 59. The outer endof the ferrule 50 is crimped or spun against the armor 49 to hold thestrips of the armor 49 from movement and to insure a good electricalcontact. The center portion of the ferrule 50 is formed into anoutwardly extending flange 52 by means of bending the ferrule 50 uponitself. The inner end 53 of the ferrule 50 covers the ends of the armor49, the braid 48 and the strip or inner conduit 44', and is turnedinwardly in the conduit 4|. The inner end 53 is pressed against theinside 41 of the conduit 4| so as to eliminate any raw edges and topresent a smooth orifice for the conductor 39.

Disposed around the insulation 40 of the conductor 39 is a conicalrubber washer 54. When a conduit 4| is connected to an outlet 33 thewasher 54 strikes the beveled face 38 of the outlet 33 and the flange5290f the ferrule 59 presses against the opposite face of the washer.The collar nut 42, when screwed onto the threads 31, forces the flange52 against the washer 54, the conical face of which is forced againstthe beveled face 38 of the outlet 33 and makes a waterproof connection.When the washer 54 is thus held under pressure it holds the insulation40, of the conductor 39 to the center of the outlet 33, thus preventingany possible friction against the inner wall of the outlet 33. thewasher 54 being compressed by the nut 42 the washer 54 exerts a pressureagainst the nut 42 and acts as a lock-washer to hold the nut firmly inplace so that the nut 42 cannot become loosened from vibration. Thissame effect is produced on all outlets where a conical washer 54 isused.

As shown in Figures 1 and 2 some of the condults 4| are shorter thanothers, for the reason that one set of conduits 4| must lead around thecylinder blocks 22 to the spark plugs on. thefar In order to retain theconduits 4| in position clips .55 and 55 are used, as best shown inFigures 11, 12 and 13. The clips 55 areused to hold the conduits 4| tothe push-rod casings 23 and comprise a single strip of spring metal, thecenter portion 58 of which is bent upon itself to surround the conduit 4A bolt 59 having a nut 60 is disposed through conduit 4|.to hold the theclip 55 adjacent the bent portion 59 securely At the same time on theconduit. The opposite portions of the clip 55 are curved as shown at 6|to surround the push-rod casings 23 and the ends 62 are flared or turnedoutward. With this construction, when it is desired to remove theconduit 4|, it is only necessary to pull the conduit 4| and the springclip 55 will bend sufliciently to release the push-rod casings 23. Inreplacing the conduit 4| the flared ends 62 will force the clip 55 openso that it may be easily slipped on and off of the push-rod casing 23.

The clips 56 are used to hold the conduit 4| to one of the cooling fins51 of the cylinder block 22. The clip 56 comprises a single strip ofspring metal bent upon itself at 63 to surround the conduit 4|, with theends 64 adjacent one cooling fin 51. A bolt 65 passes through the end 64and the fin 57 and is secured by a nut 66. In removing the conduit 4| itis necessary only to remove the bolt 65, allowing the clip 56 to remainon the conduit 4|.

From the outlets 33 the conductors 38 surrounded by the conduits 4| leadto the spark plugs of the motor. If a shielded spark-plug such as shownin Figures 3 and 8 is used the conductor 39 is attached to the plug 6'!and the conduit 4| connected to the shielding of the plug. However, itis common to use ordinary unshielded spark plugs 68 and for this purposea shield is provided to be used with such unshielded plugs, as bestshown in Figures 9 and 10. The hereinafter described shield is made sothat it may be used with any standard make of unshielded plug withoutthe necessity of changing the shielding means.

The spark plug shield (as best shown in Figures 9 and 10) is designatedgenerally as 68 and comprises an open-bottomed cup 10 adapted tosurround the spark plug 68. The cup '10 may be made longer or shorter toaccommodate various types of unshielded plugs 68. The cup 16 is providedwith an inwardly tapered bottom portion 1| so that it may be easilyseated on'the cylinder head of the engine. minates in an inturnedannularflange 12.- The flange i2 is adapted to abut the lower skirt ofthe plug68. A copper washer 13 may be secured inside the cup 10 above the flange12 so as to insure sealing contact of the plug 68 with the cylinder headof the engine. The cup." is made suificiently large to allow a socketwrench to be used to screw the plug'68 firmly into place. When the plug68 is screwed into place the cup 16 will be rigidly held thereabout, andin electrical contact with the engine. On the upper edge of the cup 10an annular projecting flange i4 is provided by bending the metal uponitself and a supporting shoulder 15 is formed by bending the metal ofthe cup 70 outward and downward. Before the end T6 of the cup 10 isturned inward as shown in Figure iii an annular L-shaped band of steelor other metal is placed in the housing formed by bending the cup 10 andthe end 16 is then bent inward to hold the ring 11 in place. With thisconstruction a firm foundation is provided for the shoulder with the useof the least possible material so as to reduce the weight. w

Disposed over the. cup 10 is a cap 18 formed or moulded of dielectricmaterial such as Bakelite. The cap 18 iselectro-plated or otherwisecovered with metallic foil or other conductive means 18 to protect thecap 18 and also to serve as an electrical conductor. On the lower end ofthe cap 16 is formed an annular depending flange with a recess 8|adjacent thereto. A special compound washer 82 is disposed in the recess8| so that The tapered portion Ii ter-' when the cap 18 is disposed onthe cup I8 the flange 14 on the cup 18 will ride against the washer 82to make a moisture-proof seal. At the same time the depending flange 80on the cap I8 will be in electrical contact with the shoulder 15 on thecup 16. A re-lnforcing member 83 is disposed in the top of the mouldedcap 18.

On one side of the cap 16 is disposed a screwthreaded bushing 84 theinner face of which is beveled as shown at 85 to receive the taperedface of a conical washer 54. The portion of the cap I8 adjacent theconical washer 54 is also beveled so that the washer 54 will make asealing contact against the cap 18 and the bushing 84. The usual collarnut 42 is used to hold the conduit 4| to the bushing 84.

Through the center of the bushing 84 and through the cap 18 is anopening 86 to accommodate the conductor 38 with the insulation 46. Theopening 86 is made at an angle to the spark plug 68 so that theconductor 38 and conduit 4| will not be bent between the outlet 33 onthe manifold 25 and the spark plug shield 68. The conductor 38 isusually made of strand wire and the ends of the strands of the conductor38 are formed into one piece by solder 81, for the purpose hereinaftershown.

Set in the moulded cap 18 immediately above the spark plug 68 is aninteriorly screw-threaded bushing 88. A screw 88 is disposed through thebushing 88 and is provided with a sharp point 88. The point 80 of thescrew 88 is adapted to be forced through the insulation 40 and makecontact with the conductor 38. The ends of the conductor 38 being heldtogether by the solder 8'I the point 88 will spread the strands of wireas it is forced through and will insure a good electrical contact.

Carried by the lower end of the screw 88 is a coil spring 8|. The upperend of the coil spring 8| may be soldered to the screw 88 and the lowerend of the spring 8| is-adapted to make contact with the stem of thespark plug 68.

The cap 18 being formed of dielectric material such as Bakelite, a shortdependent skirt 82 is provided adjacent the upper portion oi the sparkplug 68 and a second longer skirt 88 isiprovided adjacent the wall ofthe cup 16'. The skirt 82 serves as a container for the spring 8|.

The skirts 82 and 83 are adapted to .prevent high tension flashes fromthe spark plug 68 to the cup 10. In flying at high altitudes in rarefled air these flashes will occur very frequently unless some means suchas the skirts described are used to prevent them. With the spark plugshielding means here described it has been found very successful to fillthe spaces in the cup 18, designated generally as 88, with a petroleumjelly. This is made possible by reason of the fact that the cup 16 andthe cap I8 are entirely moisture-proof and will retain the petroleumjelly therein. By this method the flashes from the plug to the cup 16are eliminated and a cooling means is aiforded for the spark plug.

The cap 18 is held onto the cup 18 by means of a spring bail 84 the endsof the bail 84 being disposed through the shoulder 15 and the ring 11.In screwing the spark plug 88 into position the cup 10 will be turnedaround and the bail 84 will not always be in proper position to holddown the cap 18. Therefore, a series of openings 85 are provided so thatthe bail 84 may be placed in any desired position. The ring 1'! acts asa bearing for the bail 84 and prevents the distortion of the openings 85by the.bail 84. At the top of the ball 94 is provided a ball 96 which isfree to rotate on the bail 94. When the cap 18' With this constructionthe bail 94 will at all times hold the cap 18 firmly on the cup 10 butwill allow the cap I9 to be quickly removed at any time.

In aircraft practice dual ignition systems are often used.. Therefore,two magnetos 99 and I are provided to supply electrical impulses totheir respective series of spark plugs. In order that the wires fromthe' spark plugs may lead to the magnetos, outlets IM and I02 areprovided on the manifold 25. These outlets MI and I02 are similar totheoutlets 33 except that they are much larger in that several wires haveto pass therethrough. These outlets may be placed at any point on themanifold 25, depending upon the type of motor used and the contour ofthe manifold 25. From the outlets IOI and I02 conduits I03 and I04 leadto the two magnetos. The conduits I03 and I04 are similar inconstruction to the conduits 4I but are made larger to-accommodate morewires. The magnetos 99 and I 00 are usually located behind the engine sothat the conduits I03 and I04 lead from the manifold 25 over the engineand are held to the engine by clips I05 similar in construction to theclips 56. The conduit I03 terminates in an elbow I06 on the magneto 99and the conduit I04 terminates in an elbow I01 on the magneto I00.

Since the mode of connecting the conduits I03 and I 04 to the outletsIOI and I02 is the same as the connection between the conduits I03 andI04 and the elbows I06 and I01 only the connection to the elbow I01 willbe described. This connection is best shown in Figures 5 and 6. Aferrule I08 is disposed over the end of the conduit I04 and has itsinner end I 09 turned inside of the. conduit I04 so as to present asmooth interior surface for the conductors 39. A collar H0 is secured bybraising or other means on the ferrule I08. A collar nut I I l isprovided on the conduit I04 similar to the collar nuts 42 heretoforedescribed. The elbow I0! is provided with screwthreaded neck II2 ontowhich the collar nut III is screwed. I

A rubber gasket I I3 is disposed in the elbow I01 where said elbow I01enlarges to form the neck ing a moisture-proof joint. .At the same timethe ferrule I09, the collar H0 and the nut III acting on the neck II2,continue the electrical circuit desired. The elbow I0! is providedwithan annular projecting shoulder I I4 near its lower end, from whichshoulder II4 depends an annular flange II5. Two-piece covers II6 areprovided to cover'the. exposed portions of the magnetos 99 and I00. Thelower end III of the elbow I01 extends into the upper part of thetwo-piece covers H6 and is provided with an annular groove H8. The upperpart of the covers H6 is provided with bosses II9 from which projects aflange II9a. The flange II9a interlocks with the flange II5 on theshoulder II4 of the elbow I01, making a moisture-proof enclosure.Disposed through the bosses II9 are bolts I20 operating with nuts I2I tohold the two-piece covers l|6 firmly together. On one cover plate H6 isThe ferrule I08 is forced against the gasket I I3 and is held in placeby the nut I I I, thus makdisposed aboss I22 which carries a set-screwThe set-screw I23 projects into the groove -IIO on the elbow I01 andprevents the removal of the elbow I01 from the cover plates II6.

Inasmuch as the magnetos on various types of engines, may be in variouspositions, the groove H8 is annular so that the elbow I01 may be placedin the cover plates II6 from anyposition. Disposed on the inside of eachcover plate H6 is a leaf-spring I24 secured at one end to the coverplates II6 by rivets or other suitable means I25. When the cover platesI I6 are forced against the magnetos 99 and I00 the springs I24 willhold the cover plates II6 under tension and thus reduce. vibration andwear.

The elbow I0I is provided with several outlets I26. These outlets I26are similar to the outlets 33 on the manifold 25. Conduits I21 lead fromthe outlets I26. The conduits/I21 are similar in construction to theconduits 4|, but are made slightly larger so that one or more Wires maybe carried therethrough. The conduits I21 are provided with ferrules 50and collar nuts 42 and the connections to the outlets I06 are the sameas the connections to the manifold 25 heretofore described. One conduitI21 leads to the starting or booster magneto I28 and another conduit I2Ileads (to the switch I29. As shown in Figures 15 and 16 the conduitsI2'I may lead to the junction box I30. The junction box I30 is formed ofa piece of seamless metal tubing and is provided with outlets I3Isimilar to the outlets 33 heretofore described. The ends of the conduitsI21 that enter the starting magneto I 28 and the switch I29 may be madewith merely a ferrule I32 adapted to be frietionally held in'place byclamps I I33 on the switch I29 and the magneto I28. This construction isoptional but inasmuch as the switch I29 and. the magneto I28 are usuallymounted on the instrument panel of the aeroplane, there is very littledanger of these terminals becoming wet and they are not subject to thestrain that the other connections heretofore described are subjected to.

As shown in the lower portion of Figure 6, the' ends 81. of theconductors 39 may be provided with indicia. By having the ends of thewires numbered it is possible toquickly assemble the wiring in theshielding means without having to check each wire to find out where itshould go.

In order to have the ignition system entirely shielded it is necessaryto have the magnetos and switch shielded. This is accomplished by firstinsulating and then enclosing the parts in a continuous metal casing.When the switch or the magnetos are secured to the frame or body of theaeroplane the casings will act as a conductor. In the ordinary magnetoillustrated the operating parts are protected in the main by a" metalcasing which partially serves as a shield so that it is only necessaryto add the cover plates II6 to form a complete shield for the magnetos.As pointed out heretofore one of the objects of this invention is toprovide a system which will decrease the resistance in the high tensionconductor used. In ordinary wiring systems separate wires are run fromeach spark plug to each magneto and from each magneto to each startingor-booster magneto, and from each of the three magnetos to the switch.By the use of the junc-' tion box I30 the length of wire necessary tomake the circuits is materially reduced. Therefore, the resistance inthe wires is reduced and the ignition system will work with much greatercil'iciency.

As to the shielding p1'operties,'-it will be seen that if any electricalradiations are released anywhere between the magnetos and the sparkplugs such radiations will immediately be absorbed and grounded to theengine or fuselage of the aeroplane. Similarly, any electricalradiations coming from the outside will be absorbed and grounded beforethey can interfere with the ignition. From the foregoing it will be seenthat interference with the radio reception and equipment by the ignitionsystemis eliminated.

It is known in aircraft practice that there are sources of disturbanceof radio reception other than that directly produced by the ignitionsystem. Even with the generator magneto cut-offthere may be currentsproduced, and the broad idea of the invention described is toeffectively bond and shield all of the parts so that a continuouselectrical conductor is afforded between all metal parts to ground.Unless this is done there is varying resistance between moving, poorlybonded, or between rubbing or vibrating metal parts which causesinterference and noises in the radio receiver. Such interference anddisturbance may even be caused by the sparking of a vibrating typevoltage regulator used on the generators. To effect elimination of thisit is desirable and necessary to enclose in highly conductive casingsall parts carrying current of any description and to properly andsecurely bond at intervals to the aircraft such parts in order to obtainefficient uninterrupted radio reception.

Having thus fully described the invention what is claimed as new anddesired to be secured by Letters Patent is:

l. A radio shielding system for both the high system of an internalcombustion engine comprising a rigid manifold to enclose a plurality ofwires, flexible conduits enclosing wires from the rigid manifold to thespark plugs, conductive housings around all of the operating units ofthe ignition system and conduits enclosing wires interconnecting unitsof the ignition system, the manifold and the several conduits beingelectrically connected and grounded.

3. A radio shielding system for both the high and the low tensionportions of the entire ignition system of an internal combustion enginecomprising a rigid manifold to enclose a plurality of wires, flexibleconduits enclosing wires from the rigid manifold to the spark plugs,conductive housings around all of the operating units of the ignitionsystem, conduits enclosing wires interconnecting units of the ignitionsystem, the manition system of an internal combustion engine 4comprising a rigid manifold to enclose a plurality of ignition wires,flexible conduits to enclose some of the ignition wires and junctionboxes connected to some of the flexible conduits.

8. A radio shielding system for both the high and the low tensionportions of the entire ignition system of an internal combustion enginecomprising a rigid manifold to enclose a plurality of ignition wires,flexible conduits to enclose some of the ignition wires and junctionboxes connected to some of the flexible conduits to decrease theelectrical capacitance of the shielding system by decreasing the lengthof conduits necessary to interconnect the several magnetos and switch.

9. In a radio shield for both the high and the low tension portions ofthe entire ignition system of an internal combustion engine, a rigidmanifold and a plurality of flexible conduits to enclose all of thewires of the ignition system, said members being electrically connectedbut readily separable to permit replacement of one or more members.

10. In combination with a radial aviation engine provided with magnetos,spark plugs and a propeller, a radio shielding means for both the highand the low tension portions of the entire ignition system comprising arigid manifold disposed in front of the engine behind the propeller,said manifold being adapted to enclose and shield a plurality ofignition wires, a relatively large conduit extending over the engine toenclose and shield wires between a magneto and the manifold, flexibleconduits to enclose and shield wires between the manifold and the sparkplugs, conductive coverings around all of theoperating units of theignition system and flexible conduits to enclose and shield wiresinterconnecting the operating units of the ignition system.

11. In combination with a radial aviation engine provided with magnetos,spark plugs and a propeller, a radio shielding means for both the highand the low tension portions of the enti? ignition system comprising arigid manifold di posed in front of the engine behind the propeller,said manifold being adapted to enclose and shield a plurality ofignition wires, a relatively large flexible conduit extending over theengine to enclose and shield wires between a magneto and the manifold,relatively small flexible conduits to enclose and shield wires betweenthe manifold and the spark plugs, conductive coverings around all of theoperating units of the ignition system and flexible conduits to encloseand shield wires interconnecting the operating units'of the ignitionsystem.

12. In combination with an internal combustion engine having magnetos,booster magneto, spark plugs and switch, a radio, shielding system forboth the high and the low tension portions of the entire ignition systemcomprising a main manifold adapted to enclose a plurality ofignitionwires, a conduit connecting a magneto and the manifold andenclosing wires therebetween, flexible conduits enclosing wires fromtheman'is fold to the spark plugs, shielding coverings on the magnetos,booster magneto and switch, and flexible conduits enclosing wiresinterconnecting the magnetos, booster magneto and switch;

13. In combination with an internal combustion engine having magnetos,booster magneto, spark plugs and switch, a radio shielding system forboth the high and the'low tension portions of theentire ignition systemcomprising a main manifold adapted to enclose a plurality of ignitionwires, a conduit connecting a magneto and the manifold andenclosingwires therebetween, flexible conduits enclosing wires from themanifold to the spark plugs, shielding coverings on the magnetos,booster magneto and switch, flexible conduits enclosing wiresinterconnecting the magnetos, means to connect the flexible conduits toshielding of the spark plugs.

14. In combination with an internal combustion engine having magnetos,booster magneto,

spark plugs and switch, a radio shielding system for both the high andthe low tension portions of the entire ignition system comprising a mainmanifold adapted to enclose a plurality of ignition wires, a conduitconnecting a magneto and the manifold and enclosing wires therebetween,flexible conduits enclosing wires, from the manifold to the spark plugs,shielding coverings on the magnetos, booster'magneto and switch,flexible conduits enclosing wires interconnecting the magnetos, boostermagneto and switch and means to connect the flexible conduits toshielding of the spark plugs, all ofthe elements of the shielding systembeing connected to form a continuous shield but each element beingreadily separable from the others to permit replacement of individualelements.

15. In a radio shielding means i'or the ignition system of an internalcombustion engine, including spark plugs, magnetos with distributorblocks and high tension cables, said shielding means comprising ametallic casing means to cover and enclose thenormally exposeddistributor blocks, said casing including a rotatable elbow formationthrough which said cables are directed for connection with the sparkplugs.

16. A radio shielding means for both the high .and low tension sides ofthe entire ignition system of an internal combustion engine comprisingsectional, rigid manifolds -to enclose and electrically shield aplurality of ignition wires, flexible conduits connected to themanifolds to enclose one or more ignition wires leading to the sparkplugs and additional flexible conduits booster magneto and switch andstarting -magneto to enclose and electrically shield low tension wiringof the ignition system.

17.1A radio shielding means for both the high and low tension sides ofthe entire ignition system of aninternalcombustion engine comprisingsectional, rigid manifolds to enclose and electrically shield aplurality ofignition wires, flexible conduits connected to the manifoldsto enclose one or more ignition wires leading to the spark plugs, radioshielding on the spark plugs, and additional flexible conduits toenclose and electri- 'cally shield low tension wiring of the ignitionsystem.

18. A radio-shielding means for both the high and lowtension sides ofthe entire ignition system of an internal combustion engine comprisingsectional, rigid manifolds to enclose and electrically shield aplurality of ignition wires, flexible conduits connected to themanifolds to enclose one or more ignition wires leading to the sparkplugs,

radio shielding on the spark plugs, said flexible conduits beingconnected to the shielding of the plugs and additional flexible conduitsto enclose and electrically shield low tension wiring of theignitionsystem.

19. A radio shielding means for both the high and low tensionsides ofthe entire ignition system of an internal combustion engine) comprisingsecswitches, comprising complementary cover plates to enclose thenormally exposed distributor blocks of a magneto, a rotatable elbowassociated with the cover plates through which ignition wires pass fromthe magneto, a rigid manifold to receive a plurality of wires from therotatable elbow,

shielding means surrounding the wires between the rotatable elbow andthe manifold, flared, pro- ,7 jecting outlets on the manifold throughwhich wires extend to spark plugs, flexible conduits enclosing the wiresbetween the manifold and spark plugs, radio shielded spark plugs, saidflexible conduits being connected to the shielding qfthe plugs, metalliccasings around the switcii' and and flexible conduits enclosing wiresinterconnecting the several magnetos and switch. Josnruauascncm

